Um, seriously, what do you expect? You have created a square lattice with 27 nodes in each dimension. Had you used more points, you would have a finer grid, requiring more time and memory to generate and work with. With a truly fine enough lattice, you might not notice the jaggies. After all, pictures have curves that can look smooth, but only because they have really small pixels. But what do you expect with only 27 nodes?
You are working with what is essentially an image. Pixels are square. There is no such thing as a pixel with a curved edge.
By the way, use linspace instead!
x= -1.25:0.0932:1.25
x =
Columns 1 through 13
-1.25 -1.1568 -1.0636 -0.9704 -0.8772 -0.784 -0.6908 -0.5976 -0.5044 -0.4112 -0.318 -0.2248 -0.1316
Columns 14 through 26
-0.0384 0.0548 0.148 0.2412 0.3344 0.4276 0.5208 0.614 0.7072 0.8004 0.8936 0.9868 1.08
Column 27
1.1732
As you can see, the last point is NOT 1.25. It is 1.1732. Even if you had used a more accurate stride than 0.0932, it still would not give you the correct last point. USE LINSPACE!